Objective of this research is to seed two different types of mesenchymally originated cells on scaffolds of collagen with in situ grown hydroxyapatite, proliferate and differentiate these cells into bone and form bone tissue.Mesenchymal stem cell like cells that are isolated from menstrual blood and stem cells isolated from Wharton's jelly of umbilical cord will be used, and the proliferation rates, differentiation capacities and the bone tissue formation capability of these two cell sources will be compared.